A shake-up of relationships and health education could see children as young as four taught about looking after their mental health and staying safe on the internet.

Three new subjects are set to be introduced into the school curriculum from 2020 – relationships education from primary school, relationships and sex education at secondary school, and health education for all ages.

The new curriculum will see pupils taught the links between physical and mental health, and will cover the dangers of sexting, spotting anxiety in their friends and 'the importance of getting away from a screen'.

It will coincide with the first shake-up of sex education for two decades, a petition on which is due to be discussed in parliament on Monday.

Education secretary Damian Hinds said there was 'a lot to catch up on' in relationships education.

'Growing up and adolescence are hard enough, but the internet and social media add new pressures that just weren't there even one generation ago.

'So many things about the way people interact have changed, and this new world, seamless between online and offline, can be difficult to navigate.'

Mr Hinds said it was 'appropriate' to make health education universal alongside relationships and sex education.

'It will help children learn how to look after themselves, physically and mentally, and the importance of getting away from the screen and the headphones,' he said.

'And it can help young people be resilient as they chart a course through an ever more complex world.'

Under the plans, children as young as four will be taught self-care, such as getting enough sleep and spending time outdoors.

They will also receive lessons in online safety, such as what to do when they come across something they find uncomfortable, trolling, and chatting to strangers.

The announcement follows intense pressure for action in safeguarding vulnerable people, highlighted by the case of 14-year-old Molly Russell who killed herself in 2017. Her family found material relating to depression and suicide when they looked at her Instagram account after her death.

According to the curriculum guidelines produced on Monday, secondary school pupils will be taught about female genital mutilation (FGM) – focusing on awareness, the availability of support networks, and reminding them that it is illegal.

Students aged 11 and older should also be taught about other forms of honour-based abuse, as well as grooming, forced marriage and domestic abuse as part of a strengthened curriculum, the Department for Education said.

Teachers at secondary school will have to take lessons on online safety topics, including the serious risks of sharing private photos, the impact of viewing explicit or harmful content – including how to report it and get support – as well as how the internet can promote an unhealthy view of sex and relationships.

Anna Feuchtwang, chief executive of campaign group the National Children's Bureau, described the guidance as 'a welcome step forward in preparing children for adulthood, improving their well-being and keeping them safe and healthy'.

She said: 'By providing compulsory health education with a strong focus on mental well-being, and guaranteeing relationships education in primary schools and relationships and sex education in secondary schools, the Government has responded to the needs and concerns of children, young people and parents.

'This is an important milestone but there is further work ahead to ensure the new requirements fulfil their potential for helping children grow up healthier and happier.'